580 Tuberculosis. 



Eber's statistics covering 563 cases post-mortem findings confirmed 8i5.9% of all 

 results of tests and failed to confirm 13.1%. Carini reports still less favorable 

 results: In 361 cattle tested, post-mortem findings failed to confirm 17% of 

 diagnoses based upon the tuberculin test. In a test made by the authors and 

 covering 156 cattle, only 2% of the diagnoses failed to be confirmed at post-mortem 

 examination. Schuetz reports results of accurately controlled tests including 755 

 cattle in vifhieh T. A. was used on 255 and T. O. on 500 animals. Only 2.9% 

 of unconfirmed diagnoses were noted. Finally, of 24,784 positive reactions in cattle 

 observed in the United States from 1903 to 1908, 98.9% were confirmed on post- 

 mortem examination (Mohler). — In eohinococcus disease and in actinomycosis 

 Nocard never noted positive reactions. The authors never saw positive reactions 

 in actinomycosis. 



In the practical application of tlie tuberculin test the fact 

 should always be considered that positive reactions indicate 

 tuberculous infection merely and neither the degree nor the seat 

 of the tuberculous process. It is a notable fact also that a posi- 

 tive reaction is not necessarily the result of a clinically manifest 

 lesion which may be present, but that it may have been brought 

 about by an otherwise unimportant and inconspicuous lesion 

 in another organ of the body (of especial importance in the 

 diagnosis of tuberculosis of the udder). 



In other species of animals the tuberculin test has, in most instances, 

 given similar results. Bang found the test reliable in the horse; Eich- 

 horn obtained accurate results in three goats; in swine the test proved 

 reliable in six cases reported by Bang, in 58 cases by Mohler and 

 Schroeder, while Thlro found 21 tuberculous swine among 24 reactors. 

 According' to Thiro a rise of temperature above 103.7°, providing it 

 exceeds the pre-injection temperature by at least 1.8°, and according 

 to Schroeder and Mohler a rise of 1° should be regarded as a positive 

 reaction. In dogs the results seem to be less reliable. Although 

 Froehner noted a marked elevation of temperature (1.2° to 3.7°) in 

 eight cases, a number of tuberculous dogs did not react and in one 

 positively infected animal there was a drop of 0.7°. In other diseases, 

 excepting one case of generalized sarcomatosis, no reactions were noted. 

 Poenaru observed positive reactions in only 6 out of 13 dogs affected 

 with tuberculous exudative pleuritis. Finally, a tuberculous montey 

 tested by Froehner, receiving 0.01 gm. of tuberculin, gave a reaction 

 of 4.5° F. Hoch also observed prompt reaction in one case. 



The nature of the action of tuberculin is as yet only imperfectly 

 understood. The facl; that healthy animals may receive comparatively 

 large doses (guinea pigs 2.0 gm., dogs 1.0 gm., cattle 25 gm.) without 

 reacting or being otherwise injuriously affected, and that tuberculous 

 animals will react upon the application of much smaller doses but only 

 after a certain time has elapsed after its application, points to the 

 probability that the reaction is due to some substance which is present 

 in the body of an infected animal and with which the tuberculin com- 

 bines or in the presence of which the tuberculin forms a new substance. 



Wassermann and Bruck advance the theory that the tuberculous foci become 

 charged with body fluids and migrating blood cells under the influence of tuberculin 

 and that as a result the diseased tissue undergoes a breaking down process. Certain 

 tubercle bacilli in the tuberculous foci die off, are dissolved and extracted by the 

 neighboring cells and body fluids, their tuberculin is taken up by the surrounding 

 fluids and the production of antituberculin is the result. Injected tuberculin is 

 attracted to these foci by virtue of its avidity for its antibody; this combination 

 causes complement fixation or concentration of complement in the tuberculous tissue 

 and as a result albumin is dissolved or digested. The resulting products gain 



